The sensing bulb of a sensor is often secured to a pipe or tube. For example, the sensing bulb of a thermostatic expansion valve, TXV, is typically secured to the line between the evaporator and compressor of an air conditioning or refrigeration system. The tube and the bulb are cylindrical in cross section such that there is only line contact for thermal conduction between the members if the members are in contact and if their axes are parallel. If the axes are not parallel there would only be a point contact. Poor sensor attachment can result in failure of the TXV and the system. Changing the shape of the tube or bulb will, at best, produce two line contacts absent an exact matching of curvature between the tube and bulb. This is impractical for mass production where sensors and their bulbs come in standard sizes and where modification of the tubing introduces a restriction and would not be made to the necessary tolerances in a mass production situation.